Willie Johnson was arrested on June 10, 2015 and charged with manslaugher in the beating death of his girlfriend, Suffolk prosecutors said. Photo Credit: NYSDCCS

The man known long ago as the "Wyandanch railroad rapist" is behind bars again, this time charged with beating his girlfriend to death.

Willie Johnson, 59, served more than 18 years in prison after he was convicted of a series of knifepoint rapes, most of them near the Wyandanch train station in 1979 and 1980. Now he is charged with first-degree manslaughter in the death of Thelma Stewart, 49, of Wyandanch.

When Johnson was arrested in the rape spree in 1980, police said he could have killed any one of his victims. In each of his attacks, he held a folding knife with a 4-inch blade to his victim's throat.

"This was a very dangerous man. . . . It was a quirk of his, he would make a superficial cut on the victim's throat," Suffolk Det. Joseph Maniec said in November 1980, after Johnson's arrest. "We had a potential murder going here."

One victim told police Johnson had told her "he had killed a punk, and it didn't matter if he killed me."

He attacked most of his victims as they walked from an evening train to their cars in the station parking lot, police said then. He was charged with raping three women and assaulting a fourth, but police said then he was a suspect in eight other attacks.

Johnson's latest charge is the result of a beating that took place from May 12 into May 13, Assistant District Attorney Raphael Pearl said after the arraignment. "He continually beat his girlfriend," Pearl said. Stewart died several days later, he said.

"He can't run away from his past, but he's paid his proverbial debt to society," Mates said. "He absolutely, 100 percent, vehemently denies these allegations. He absolutely denies laying a hand on her."

Mates said in an interview Stewart had health problems because of "an extreme drinking problem" and suggested that may have contributed to her death.

Pearl said Stewart's autopsy showed alcohol-related liver damage, but that wasn't the cause of her death. Other tenants in the house where Johnson and Stewart rented a room "heard the beating going on," Pearl said.

Johnson fled the scene and later made admissions after he was found with what appeared to be blood on his shirt, Pearl said.